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To Charles Lyell 12 July [1872]1

Down, | Beckenham, Kent.

July 12th

My dear Lyell

I have been glad to see the enclosed & returned.—2 It seems to me very cool in Agassiz to doubt the recent upheaval of Patagonia, without having visited any part; & he entirely misrepresents me in saying that I infer upheaval from the form of the land, as I trusted entirely to shells embedded & on the surface. It is simply monstrous to suppose that the terraces stretching on a dead level for leagues along the coast, & miles in breadth, & covered with beds of stratified gravel 10–30 feet in thickness, are due to subaerial denudation.3

As for the pond of salt water, twice or thrice the density of sea-water, & nearly dry, containing sea-shells in same relative proportions as on the adjoining coast, it almost passes my belief.4 Could there have been a lively midshipman on board, who in the morning stocked the pool from the adjoining coast?

As for glaciation I will not venture to express any opinion, for when in S. America I knew nothing about glaciers, & perhaps attributed much icebergs which ought to be attributed to glaciers.5 On the other hand Agassiz seems to me mad about glaciers, & apparently never thinks of drift ice.— I did see one clear case of former greater extension of a glacier in T. del Fuego.—6

I hope that you are enjoying your holiday.

My dear Lyell | Yours affectionately | Ch. Darwin

Footnotes

Lyell evidently sent CD a copy of an article from the New York Tribune, 26 June 1872, in which some of Louis Agassiz’s conclusions regarding glacial action in Patagonia were published (J. L. R. Agassiz 1872a). This article was reprinted in Nature in two parts, 11 and 18 July 1872 (J. L. R. Agassiz 1872b), but the reference cannot be to Agassiz 1872b as the part of the paper describing the topics mentioned by CD was not published until 18 July. Agassiz was a member of the deep-sea dredging expedition to South America aboard the US coast survey steamer Hassler from December 1871 to August 1872 (E. C. Agassiz 1885, 2: 697–764).

In March 1872, while the Hassler was anchored off Cliff End in the Gulf of San Mathias, Patagonia, Agassiz made observations on the tertiary deposits of Patagonia that were inconsistent with CD’s view (see J. L. R. Agassiz 1872a, pp. 1–2). Agassiz considered the voyage an opportunity to test evolutionary theory (Lurie 1959, p. 106).

Agassiz argued that the whole southern extremity of South America exhibited the effects of glacial action, and that the angled scratches and furrows in the rocks of Chatham Island showed that they could not have been made by floating ice but only from the pressure of an ice sheet moving from the south-east to the north-west (J. L. R. Agassiz 1872a, p. 2).